OBJECTIVE: To synthesize compounds which several workers need for the evaluation of carcinogenic activity, in particular all of the nuclear methoxy-7,12-dimethylbenz(a)-anthracenes. APPROACH AND PROGRESS: The synthesis of 5-hydroxy-7,12-dimethylbenz(a)anthracene, -7-methylbenz(a)anthracene, -12-methylbenz(a)anthracene has been accomplished. The tendency of these compounds to react in the keto form is being assessed, as the keto form may be the oxygenated precursor which interacts with DNA and/or RNA to initiate cancer.